Power density (horsepower output divided by weight) improvement efforts in the past have been directed to reductions in size and/or increasing the efficiency of the turbine or the generator as separate entities in the turboelectric art. Still other attempts to increase the power density of such combined elements have been directed to improvements in shaft coupling devices, packing seals, bearings or the reduction of the overall numbers of such devices so as to reduce friction or leakage and thus improve the overall turbine generator or compressor set efficiency.
The objective of our invention is to improve the set performance of motor driven compressors and pumps or turbine generators while reducing size and weight by integrating the component involved with the motion of the fluid (turbine, compressor or pump) and the electrical component (generator or motor) into one piece. The integration is obtained by running the turbine, pump or compressor inside of a generator/motor or, conversely, by running the generator/motor inside of a turbine, pump or compressor. Such integration results in a single combined rotor, one set of bearings instead of two, and the elimination of a coupling requirement between the turbine and generator or motor. Additionally, no shafts protrude through casings and, therefore, shaft seals are eliminated. The reduced number of bearings and the elimination of shaft seals inherently reduce friction and leakage losses which lead to an increase in efficiency. Moreover, the reduction in weight of the integrated unit also leads to increased efficiency. Of equal importance, however, is the reduction in overall space or machinery "footprint" requirements which are particularly important in commercial applications such as oil drilling platforms and shipboard engine rooms, for example, where space is at a premium. These and further objects and advantages of the present invention will become more apparent upon reference to the following specification, appended claims and drawings.